1. Technical Field
The present invention relates to a reservoir tank that stores hydraulic fluid and is used in a hydraulic pressure-actuated device such as a hydraulic brake device that utilizes hydraulic pressure such as oil pressure and to the technical field of a brake device equipped with the reservoir tank.
2. Related Art
Conventionally, in vehicles such as automobiles, there are vehicles that employ a hydraulic brake device as a hydraulic pressure-actuated device that utilizes hydraulic pressure. In this hydraulic brake device, there is used a reservoir tank that stores hydraulic fluid supplied to a master cylinder that generates hydraulic pressure.
As a conventional reservoir tank, there is known a reservoir tank that is equipped with a hydraulic fluid supply portion to which hydraulic fluid is supplied from a hydraulic fluid supply opening that is an open end of a cylindrical member via this cylindrical member, a hydraulic fluid storage chamber that stores the hydraulic fluid supplied to a fluid chamber of a master cylinder, a hydraulic fluid passage that allows the hydraulic fluid supply portion and the hydraulic fluid storage chamber to be communicated with each other and through which the hydraulic fluid flows from the hydraulic fluid supply portion to the hydraulic fluid storage chamber, and a cap that opens and closes the hydraulic fluid supply opening (e.g., see JP-A-2006-519728).
In the reservoir tank described in JP-A-2006-519728, in a state where the reservoir tank has been installed in a vehicle, the hydraulic fluid supply opening and the hydraulic fluid supply portion are positioned on the vehicle front side of the hydraulic fluid storage chamber. The reservoir tank is installed in a limited space of a relatively narrow engine room; thus, sometimes other parts of the vehicle such as a dashboard are positioned above the hydraulic fluid storage chamber and replenishment of the inside of the reservoir tank with the hydraulic fluid becomes difficult, so the hydraulic fluid supply opening and the hydraulic fluid supply portion are disposed on the vehicle front side of the hydraulic fluid storage chamber in order to make it easier to replenish the reservoir tank with the hydraulic fluid.
In the reservoir tank described in JP-A-2006-519728, in a state where the reservoir tank has been installed in a vehicle, the maximum storage level (MAX line) of the hydraulic fluid is set in a middle position in the height direction (vertical direction) of the hydraulic fluid supply portion below the cylindrical member. By setting the MAX line in this manner, an air chamber is formed inside the hydraulic fluid supply portion and inside the cylindrical member above the hydraulic fluid stored to the MAX line. This air chamber is ordinarily set to be at atmospheric pressure, and when the volume of the hydraulic fluid changes because of a rise in the temperature of the hydraulic fluid or the like, the air inside the air chamber is supplied and exhausted by a cap seal disposed in the hydraulic fluid supply opening, whereby the volume change in the hydraulic fluid is absorbed.
In order to supply hydraulic fluid to a reservoir tank installed in a vehicle, usually a hydraulic fluid pressure-feed filling device is used to fill the inside of the reservoir tank with the hydraulic fluid. In that case, reservoir tanks of various shapes and structures are manufactured depending on the vehicle type. Consequently, the distance between the MAX line in the reservoir tank and the hydraulic fluid supply opening variously differ, so a pressure-feed filling device instrument cannot be commonly used in the different reservoir tanks and is created depending on the type of the reservoir tank.
Incidentally, depending on the use environment of the vehicle (e.g., a large temperature rise inside the engine room), an even larger air chamber than the one in the reservoir tank described in JP-T-2006-519728 is required. Thus, it is conceivable to increase the volume of the air chamber by maintaining the MAX line as is and simply increasing the length of the cylindrical member and the height of the portion of the hydraulic fluid supply portion above the MAX line.
However, when the length of the cylindrical member and the height of the hydraulic fluid supply portion are simply increased, the height of the hydraulic fluid supply opening from the MAX line also ends up becoming higher. In other words, the distance between the MAX line and the hydraulic fluid supply opening becomes longer. For this reason, there is the problem that the pressure-feed filling device instrument cannot be used as is, which necessitates changing the pressure-feed filling device instrument—that is, creating a new instrument Moreover, there is also the problem that, when the vehicle production line is a line that continuously produces different vehicle types, various types of pressure-feed filling device instruments have to be prepared for the production line, and so not only does work become cumbersome but there arises the potential to misuse an instrument.